Certgen

Certgen is a Ruby CLI tool to generate free SSL certificates from Let's Encrypt using DNS-01 verification. Perfect for developers and site owners who use cPanel or manually managed servers and need to upload certificates themselves.

✨ Features

✅ Generate valid SSL certificates via Let's Encrypt
🌐 Supports both base domains and www. subdomains automatically
🔐 Uses DNS-01 challenge (great for wildcard and shared hosting)
📁 Outputs .crt, .pem, and zipped bundles for easy upload
🔄 Stores reusable Let's Encrypt account key
🖥️ CLI interface for quick and easy usage

📦 Installation

gem install certgen

🚀 Usage

🔧 Testing with Let’s Encrypt Production

Run the CLI tool from your terminal:

certgen --domain example.com --email user@example.com

This above command will overall:

Generate or reuse your Let's Encrypt account key
Create DNS-01 challenge instructions
Wait for your confirmation after DNS is set
Generate the certificate files
Zip them for upload to cPanel or any hosting service

🔧 Testing with Let’s Encrypt Staging

To avoid hitting rate limits during development or testing, use the Let’s Encrypt staging environment:

certgen test --domain example.com --email you@example.com

This runs the same generation process but against the staging ACME server.
Useful for verifying DNS setup and automation without generating real certificates.

🔄 Example Output Files

After running, your certs will be saved in:

~/.ssl_output/example.com/
├── certificate.crt
├── private_key.pem
├── ca_bundle.pem
└── cert_bundle.zip

✍️ DNS Setup

You'll be prompted to create a DNS TXT record:

Record Name: _acme-challenge.example.com
Record Type: TXT
Record Value: abc123...

Use https://dnschecker.org to confirm propagation before continuing.

🔧 Development

Clone and run locally:

git clone https://github.com/cdrrazan/certgen
cd certgen
bundle install

Run the CLI locally:

bin/certgen --domain example.com --email user@example.com

✅ Requirements

Ruby >= 3
DNS management access to create TXT records
cPanel or similar manual SSL upload support

📄 License

This project is licensed under the MIT License. See the LICENSE file for details.

🙌 Author

Rajan Bhattarai
GitHub • Email

🛠 Contributions and issues are welcome — feel free to open a PR or issue on GitHub!

certgen

Runtime